1gitremote-helpers(1) 2==================== 3 4NAME 5---- 6gitremote-helpers - Helper programs to interact with remote repositories 7 8SYNOPSIS 9-------- 10[verse] 11'git remote-<transport>' <repository> [<URL>] 12 13DESCRIPTION 14----------- 15 16Remote helper programs are normally not used directly by end users, 17but they are invoked by Git when it needs to interact with remote 18repositories Git does not support natively. A given helper will 19implement a subset of the capabilities documented here. When Git 20needs to interact with a repository using a remote helper, it spawns 21the helper as an independent process, sends commands to the helper's 22standard input, and expects results from the helper's standard 23output. Because a remote helper runs as an independent process from 24Git, there is no need to re-link Git to add a new helper, nor any 25need to link the helper with the implementation of Git. 26 27Every helper must support the "capabilities" command, which Git 28uses to determine what other commands the helper will accept. Those 29other commands can be used to discover and update remote refs, 30transport objects between the object database and the remote repository, 31and update the local object store. 32 33Git comes with a "curl" family of remote helpers, that handle various 34transport protocols, such as 'git-remote-http', 'git-remote-https', 35'git-remote-ftp' and 'git-remote-ftps'. They implement the capabilities 36'fetch', 'option', and 'push'. 37 38INVOCATION 39---------- 40 41Remote helper programs are invoked with one or (optionally) two 42arguments. The first argument specifies a remote repository as in Git; 43it is either the name of a configured remote or a URL. The second 44argument specifies a URL; it is usually of the form 45'<transport>://<address>', but any arbitrary string is possible. 46The 'GIT_DIR' environment variable is set up for the remote helper 47and can be used to determine where to store additional data or from 48which directory to invoke auxiliary Git commands. 49 50When Git encounters a URL of the form '<transport>://<address>', where 51'<transport>' is a protocol that it cannot handle natively, it 52automatically invokes 'git remote-<transport>' with the full URL as 53the second argument. If such a URL is encountered directly on the 54command line, the first argument is the same as the second, and if it 55is encountered in a configured remote, the first argument is the name 56of that remote. 57 58A URL of the form '<transport>::<address>' explicitly instructs Git to 59invoke 'git remote-<transport>' with '<address>' as the second 60argument. If such a URL is encountered directly on the command line, 61the first argument is '<address>', and if it is encountered in a 62configured remote, the first argument is the name of that remote. 63 64Additionally, when a configured remote has 'remote.<name>.vcs' set to 65'<transport>', Git explicitly invokes 'git remote-<transport>' with 66'<name>' as the first argument. If set, the second argument is 67'remote.<name>.url'; otherwise, the second argument is omitted. 68 69INPUT FORMAT 70------------ 71 72Git sends the remote helper a list of commands on standard input, one 73per line. The first command is always the 'capabilities' command, in 74response to which the remote helper must print a list of the 75capabilities it supports (see below) followed by a blank line. The 76response to the capabilities command determines what commands Git uses 77in the remainder of the command stream. 78 79The command stream is terminated by a blank line. In some cases 80(indicated in the documentation of the relevant commands), this blank 81line is followed by a payload in some other protocol (e.g., the pack 82protocol), while in others it indicates the end of input. 83 84Capabilities 85~~~~~~~~~~~~ 86 87Each remote helper is expected to support only a subset of commands. 88The operations a helper supports are declared to Git in the response 89to the `capabilities` command (see COMMANDS, below). 90 91In the following, we list all defined capabilities and for 92each we list which commands a helper with that capability 93must provide. 94 95Capabilities for Pushing 96^^^^^^^^^^^^^^^^^^^^^^^^ 97'connect':: 98 Can attempt to connect to 'git receive-pack' (for pushing), 99 'git upload-pack', etc for communication using 100 git's native packfile protocol. This 101 requires a bidirectional, full-duplex connection. 102+ 103Supported commands: 'connect'. 104 105'push':: 106 Can discover remote refs and push local commits and the 107 history leading up to them to new or existing remote refs. 108+ 109Supported commands: 'list for-push', 'push'. 110 111'export':: 112 Can discover remote refs and push specified objects from a 113 fast-import stream to remote refs. 114+ 115Supported commands: 'list for-push', 'export'. 116 117If a helper advertises 'connect', Git will use it if possible and 118fall back to another capability if the helper requests so when 119connecting (see the 'connect' command under COMMANDS). 120When choosing between 'push' and 'export', Git prefers 'push'. 121Other frontends may have some other order of preference. 122 123'no-private-update':: 124 When using the 'refspec' capability, git normally updates the 125 private ref on successful push. This update is disabled when 126 the remote-helper declares the capability 'no-private-update'. 127 128 129Capabilities for Fetching 130^^^^^^^^^^^^^^^^^^^^^^^^^ 131'connect':: 132 Can try to connect to 'git upload-pack' (for fetching), 133 'git receive-pack', etc for communication using the 134 Git's native packfile protocol. This 135 requires a bidirectional, full-duplex connection. 136+ 137Supported commands: 'connect'. 138 139'fetch':: 140 Can discover remote refs and transfer objects reachable from 141 them to the local object store. 142+ 143Supported commands: 'list', 'fetch'. 144 145'import':: 146 Can discover remote refs and output objects reachable from 147 them as a stream in fast-import format. 148+ 149Supported commands: 'list', 'import'. 150 151'check-connectivity':: 152 Can guarantee that when a clone is requested, the received 153 pack is self contained and is connected. 154 155If a helper advertises 'connect', Git will use it if possible and 156fall back to another capability if the helper requests so when 157connecting (see the 'connect' command under COMMANDS). 158When choosing between 'fetch' and 'import', Git prefers 'fetch'. 159Other frontends may have some other order of preference. 160 161Miscellaneous capabilities 162^^^^^^^^^^^^^^^^^^^^^^^^^^ 163 164'option':: 165 For specifying settings like `verbosity` (how much output to 166 write to stderr) and `depth` (how much history is wanted in the 167 case of a shallow clone) that affect how other commands are 168 carried out. 169 170'refspec' <refspec>:: 171 For remote helpers that implement 'import' or 'export', this capability 172 allows the refs to be constrained to a private namespace, instead of 173 writing to refs/heads or refs/remotes directly. 174 It is recommended that all importers providing the 'import' 175 capability use this. It's mandatory for 'export'. 176+ 177A helper advertising the capability 178`refspec refs/heads/*:refs/svn/origin/branches/*` 179is saying that, when it is asked to `import refs/heads/topic`, the 180stream it outputs will update the `refs/svn/origin/branches/topic` 181ref. 182+ 183This capability can be advertised multiple times. The first 184applicable refspec takes precedence. The left-hand of refspecs 185advertised with this capability must cover all refs reported by 186the list command. If no 'refspec' capability is advertised, 187there is an implied `refspec *:*`. 188+ 189When writing remote-helpers for decentralized version control 190systems, it is advised to keep a local copy of the repository to 191interact with, and to let the private namespace refs point to this 192local repository, while the refs/remotes namespace is used to track 193the remote repository. 194 195'bidi-import':: 196 This modifies the 'import' capability. 197 The fast-import commands 'cat-blob' and 'ls' can be used by remote-helpers 198 to retrieve information about blobs and trees that already exist in 199 fast-import's memory. This requires a channel from fast-import to the 200 remote-helper. 201 If it is advertised in addition to "import", Git establishes a pipe from 202 fast-import to the remote-helper's stdin. 203 It follows that Git and fast-import are both connected to the 204 remote-helper's stdin. Because Git can send multiple commands to 205 the remote-helper it is required that helpers that use 'bidi-import' 206 buffer all 'import' commands of a batch before sending data to fast-import. 207 This is to prevent mixing commands and fast-import responses on the 208 helper's stdin. 209 210'export-marks' <file>:: 211 This modifies the 'export' capability, instructing Git to dump the 212 internal marks table to <file> when complete. For details, 213 read up on '--export-marks=<file>' in linkgit:git-fast-export[1]. 214 215'import-marks' <file>:: 216 This modifies the 'export' capability, instructing Git to load the 217 marks specified in <file> before processing any input. For details, 218 read up on '--import-marks=<file>' in linkgit:git-fast-export[1]. 219 220'signed-tags':: 221 This modifies the 'export' capability, instructing Git to pass 222 '--signed-tags=verbatim' to linkgit:git-fast-export[1]. In the 223 absence of this capability, Git will use '--signed-tags=warn-strip'. 224 225 226 227COMMANDS 228-------- 229 230Commands are given by the caller on the helper's standard input, one per line. 231 232'capabilities':: 233 Lists the capabilities of the helper, one per line, ending 234 with a blank line. Each capability may be preceded with '*', 235 which marks them mandatory for Git versions using the remote 236 helper to understand. Any unknown mandatory capability is a 237 fatal error. 238+ 239Support for this command is mandatory. 240 241'list':: 242 Lists the refs, one per line, in the format "<value> <name> 243 [<attr> ...]". The value may be a hex sha1 hash, "@<dest>" for 244 a symref, or "?" to indicate that the helper could not get the 245 value of the ref. A space-separated list of attributes follows 246 the name; unrecognized attributes are ignored. The list ends 247 with a blank line. 248+ 249See REF LIST ATTRIBUTES for a list of currently defined attributes. 250+ 251Supported if the helper has the "fetch" or "import" capability. 252 253'list for-push':: 254 Similar to 'list', except that it is used if and only if 255 the caller wants to the resulting ref list to prepare 256 push commands. 257 A helper supporting both push and fetch can use this 258 to distinguish for which operation the output of 'list' 259 is going to be used, possibly reducing the amount 260 of work that needs to be performed. 261+ 262Supported if the helper has the "push" or "export" capability. 263 264'option' <name> <value>:: 265 Sets the transport helper option <name> to <value>. Outputs a 266 single line containing one of 'ok' (option successfully set), 267 'unsupported' (option not recognized) or 'error <msg>' 268 (option <name> is supported but <value> is not valid 269 for it). Options should be set before other commands, 270 and may influence the behavior of those commands. 271+ 272See OPTIONS for a list of currently defined options. 273+ 274Supported if the helper has the "option" capability. 275 276'fetch' <sha1> <name>:: 277 Fetches the given object, writing the necessary objects 278 to the database. Fetch commands are sent in a batch, one 279 per line, terminated with a blank line. 280 Outputs a single blank line when all fetch commands in the 281 same batch are complete. Only objects which were reported 282 in the output of 'list' with a sha1 may be fetched this way. 283+ 284Optionally may output a 'lock <file>' line indicating a file under 285GIT_DIR/objects/pack which is keeping a pack until refs can be 286suitably updated. 287+ 288If option 'check-connectivity' is requested, the helper must output 289'connectivity-ok' if the clone is self-contained and connected. 290+ 291Supported if the helper has the "fetch" capability. 292 293'push' +<src>:<dst>:: 294 Pushes the given local <src> commit or branch to the 295 remote branch described by <dst>. A batch sequence of 296 one or more 'push' commands is terminated with a blank line 297 (if there is only one reference to push, a single 'push' command 298 is followed by a blank line). For example, the following would 299 be two batches of 'push', the first asking the remote-helper 300 to push the local ref 'master' to the remote ref 'master' and 301 the local 'HEAD' to the remote 'branch', and the second 302 asking to push ref 'foo' to ref 'bar' (forced update requested 303 by the '+'). 304+ 305------------ 306push refs/heads/master:refs/heads/master 307push HEAD:refs/heads/branch 308\n 309push +refs/heads/foo:refs/heads/bar 310\n 311------------ 312+ 313Zero or more protocol options may be entered after the last 'push' 314command, before the batch's terminating blank line. 315+ 316When the push is complete, outputs one or more 'ok <dst>' or 317'error <dst> <why>?' lines to indicate success or failure of 318each pushed ref. The status report output is terminated by 319a blank line. The option field <why> may be quoted in a C 320style string if it contains an LF. 321+ 322Supported if the helper has the "push" capability. 323 324'import' <name>:: 325 Produces a fast-import stream which imports the current value 326 of the named ref. It may additionally import other refs as 327 needed to construct the history efficiently. The script writes 328 to a helper-specific private namespace. The value of the named 329 ref should be written to a location in this namespace derived 330 by applying the refspecs from the "refspec" capability to the 331 name of the ref. 332+ 333Especially useful for interoperability with a foreign versioning 334system. 335+ 336Just like 'push', a batch sequence of one or more 'import' is 337terminated with a blank line. For each batch of 'import', the remote 338helper should produce a fast-import stream terminated by a 'done' 339command. 340+ 341Note that if the 'bidi-import' capability is used the complete batch 342sequence has to be buffered before starting to send data to fast-import 343to prevent mixing of commands and fast-import responses on the helper's 344stdin. 345+ 346Supported if the helper has the "import" capability. 347 348'export':: 349 Instructs the remote helper that any subsequent input is 350 part of a fast-import stream (generated by 'git fast-export') 351 containing objects which should be pushed to the remote. 352+ 353Especially useful for interoperability with a foreign versioning 354system. 355+ 356The 'export-marks' and 'import-marks' capabilities, if specified, 357affect this command in so far as they are passed on to 'git 358fast-export', which then will load/store a table of marks for 359local objects. This can be used to implement for incremental 360operations. 361+ 362Supported if the helper has the "export" capability. 363 364'connect' <service>:: 365 Connects to given service. Standard input and standard output 366 of helper are connected to specified service (git prefix is 367 included in service name so e.g. fetching uses 'git-upload-pack' 368 as service) on remote side. Valid replies to this command are 369 empty line (connection established), 'fallback' (no smart 370 transport support, fall back to dumb transports) and just 371 exiting with error message printed (can't connect, don't 372 bother trying to fall back). After line feed terminating the 373 positive (empty) response, the output of service starts. After 374 the connection ends, the remote helper exits. 375+ 376Supported if the helper has the "connect" capability. 377 378If a fatal error occurs, the program writes the error message to 379stderr and exits. The caller should expect that a suitable error 380message has been printed if the child closes the connection without 381completing a valid response for the current command. 382 383Additional commands may be supported, as may be determined from 384capabilities reported by the helper. 385 386REF LIST ATTRIBUTES 387------------------- 388 389The 'list' command produces a list of refs in which each ref 390may be followed by a list of attributes. The following ref list 391attributes are defined. 392 393'unchanged':: 394 This ref is unchanged since the last import or fetch, although 395 the helper cannot necessarily determine what value that produced. 396 397OPTIONS 398------- 399 400The following options are defined and (under suitable circumstances) 401set by Git if the remote helper has the 'option' capability. 402 403'option verbosity' <n>:: 404 Changes the verbosity of messages displayed by the helper. 405 A value of 0 for <n> means that processes operate 406 quietly, and the helper produces only error output. 407 1 is the default level of verbosity, and higher values 408 of <n> correspond to the number of -v flags passed on the 409 command line. 410 411'option progress' \{'true'|'false'\}:: 412 Enables (or disables) progress messages displayed by the 413 transport helper during a command. 414 415'option depth' <depth>:: 416 Deepens the history of a shallow repository. 417 418'option followtags' \{'true'|'false'\}:: 419 If enabled the helper should automatically fetch annotated 420 tag objects if the object the tag points at was transferred 421 during the fetch command. If the tag is not fetched by 422 the helper a second fetch command will usually be sent to 423 ask for the tag specifically. Some helpers may be able to 424 use this option to avoid a second network connection. 425 426'option dry-run' \{'true'|'false'\}: 427 If true, pretend the operation completed successfully, 428 but don't actually change any repository data. For most 429 helpers this only applies to the 'push', if supported. 430 431'option servpath <c-style-quoted-path>':: 432 Sets service path (--upload-pack, --receive-pack etc.) for 433 next connect. Remote helper may support this option, but 434 must not rely on this option being set before 435 connect request occurs. 436 437'option check-connectivity' \{'true'|'false'\}:: 438 Request the helper to check connectivity of a clone. 439 440'option force' \{'true'|'false'\}:: 441 Request the helper to perform a force update. Defaults to 442 'false'. 443 444SEE ALSO 445-------- 446linkgit:git-remote[1] 447 448linkgit:git-remote-testgit[1] 449 450GIT 451--- 452Part of the linkgit:git[1] suite